1. Field of the Invention
This invention relates to hydraulic throttles and particularly to hydraulic throttles for motorcycles and the like.
2. Description of the Prior Art
Motorcycles, three wheelers, and other types of all terrain vehicles are typically operated by a hand-operated throttle that is placed on a vehicle's handlebar. These throttles are cylinders that extend outward from the handlebar. The user typically grips the throttle and rotates it from front to back. The throttle is connected to a cable that extends from the handlebar to the engine, where it connects to the throttle plate control. As the throttle is turned, the cable is extended or contracted. This, in turn, opens and closes the throttle plate on the engine. The problem with this design is that it relies on a cable that is normally exposed as it travels from the handlebars down to the engine. Although the cable is often secured to the frame, it is exposed to damage, and to the elements. Thus, it becomes a maintenance item. From an aesthetic point of view, it is also not attractive to have cables hanging from the handlebars as it often detracts from the appearance of the motorcycle.
Placing the throttle cable within the handlebar removes the cable from view. It also protects it from damage and exposure. To install the cable in the handlebar, however, it is necessary to modify the throttle grip itself to accommodate this change. One such change involves the use of hydraulics. For example, U.S. Pat. No. 4,633,726 to Chang teaches a hydraulic throttle for use on motorcycles. It uses a throttle grip that contains hydraulic piston system. These pistons are connected to hydraulic lines that feed into a second hydraulic system that operates the throttle. Another example of hydraulic control is found in U.S. Pat. No. 5,443,134 to Gajak et al. In this patent, a bicycle hand break is attached to a hydraulic cylinder that is then connected by a hydraulic line to the main hydraulic operating system on the bicycle break.
Both of these systems substitute hydraulic lines for cables. Although this is one solution, it is not necessarily a good one. Replacing the cables with hydraulic lines adds to the complexity of the system, as well as replacing one maintenance problem with an even bigger one.